INFLAMMATORY BOWEL-DISEASE AND DOMESTIC HYGIENE IN INFANCY

To test the hypothesis that Crohn's disease is caused by delayed expos ure to enteric infections, we did a case-control study. We compared 13 3 patients who have Crohn's disease and 231 with ulcerative colitis wh o have controls selected from the general population and matched for a ge and sex. Crohn's disease was more common in subjects whose first ho uses had a hot-water tap (odds ratio 5.0, 95% CI 1.4-17.3) and separat e bathroom (3.3, 1.3-8.3). Ulcerative colitis showed no clear relation to household amenities in infancy. These findings may explain why the incidence of Crohn's disease has increased in developed countries ove r the past 50 years.